Lactobacillus GG in the prevention of antibiotic-associated diarrhea in children

Living drugs for gastrointestinal diseases: the case for probiotics

Nonpathogenic micro-organisms may contain or produce molecules of potential therapeutic interest. This led to the concept of using ingested living micro-organisms to produce and transport these molecules to targets in the proximal or distal intestine. Several characteristics of this pharmacological approach are very original: potential for in vivo production of active molecules, for targeting immune cells, for presenting immunogenic molecules in a microbial context, for duodenal delivery using bile sensitivity. Probiotics have been studied for some decades and more recently worm eggs have also received some interest. This paper summarizes facts (especially results of randomized controlled trials and pharmacokinetic studies), and ideas about the use of probiotics to treat or prevent gastrointestinal diseases. The safety of this approach (exceptional cases of infections have been observed), and the potential for using new agents or genetically modified micro-organisms (ongoing trials in humans with Crohn's disease) are also discussed.

Probiotics: facts and myths

In recent years there has been a significant upsurge in research on the characterisation and verification of the potential health benefits associated with the use of probiotics. In addition, the market for probiotics continues to expand exponentially as consumers (mostly healthy individuals) rely on health claims made by manufacturers to make their choices. This review appraises the available evidence for and against the health claims associated with probiotics. The use of probiotics in promoting gastrointestinal health and immunity, and their use in the prevention of urogenital infections, allergies and cancer are reviewed. Furthermore, issues surrounding the use of probiotics in healthy individuals, the safety of probiotics and regulatory concerns are addressed. There is scientific evidence that specific strains of probiotic microorganisms confer health benefits on the host and are safe for human use. However, this evidence cannot be extrapolated to other strains, as these effects are strain-specific. Probiotics have potential health benefits for conditions such as gastrointestinal infections, genitourinary infections, allergies and certain bowel disorders, all of which afflict a considerable proportion of the global population. However, considerable work is still needed to confirm these potential health benefits.

Soluble factors from Lactobacillus GG activate MAPKs and induce cytoprotective heat shock proteins in intestinal epithelial cells

Conditioned media from the probiotic Lactobacillus GG (LGG-CM) induce heat shock protein (Hsp) expression in intestinal epithelial cells. LGG-CM induces both Hsp25 and Hsp72 in a time- and concentration-dependent manner. These effects are mediated by a low-molecular-weight peptide that is acid and heat stable. DNA microarray experiments demonstrate that Hsp72 is one of the most highly upregulated genes in response to LGG-CM treatment. Real-time PCR and electrophoretic mobility shift assay confirm that regulation of Hsp induction is at least in part transcriptional in nature, involving heat shock factor-1. Although Hsps are not induced for hours after exposure, transient exposure to LGG-CM is sufficient to initiate the signal for Hsp induction, suggesting that signal transduction pathways may be involved. Experiments confirm that LGG-CM modulates the activity of certain signaling pathways in intestinal epithelial cells by activating MAP kinases. Inhibitors of p38 and JNK block the expression of Hsp72 normally induced by LGG-CM. Functional studies indicate that LGG-CM treatment of gut epithelial cells protects them from oxidant stress, perhaps by preserving cytoskeletal integrity. By inducing the expression of cytoprotective Hsps in gut epithelial cells, and by activating signal transduction pathways, the peptide product(s) secreted by LGG may contribute to the beneficial clinical effects attributed to this probiotic.

Probiotics down-regulate flaA sigma28 promoter in Campylobacter jejuni

Lactobacilli and bifidobacteria are important members of the gastrointestinal microflora of humans and animals and are thought to have positive effects on human health. Therefore, there is an increasing interest in using these microorganisms as probiotics to be incorporated into either fermented dairy products or tablets. However, convincing scientific data that support claims of their health benefits are scarce. The effect of cell-free extracts of milk fermented by 10 probiotic bacteria (five Bifidobacterium strains and five Lactobacillus strains) on the expression of the flaA gene of Campylobacter jejuni was assessed using a fusion between the flaA sigma28 promoter and a promoterless luxCDABE cassette carried on the plasmid pRYluxCDABE, which resulted in strains with quantifiable luminescence linked to flaA sigma28 promoter activity. Cell-free extracts of milk fermented by all of the tested probiotic strains inhibited the growth of the C. jejuni and down-regulatedflaA sigma28 promoter activity. Two nonprobiotic lactic acid bacterial strains, Lactococcus lactis and Streptococcus thermophilus, were less inhibitory.

Probiotic therapy for the prevention and treatment of Clostridium difficile-associated diarrhea: a systematic review

BACKGROUND

The recent increase in the number and severity of cases of nosocomial Clostridium difficile-associated diarrhea (CDAD) has prompted interest in the use of probiotics for the prevention and treatment of this disease. We performed a systematic review of randomized controlled trials to assess the effectiveness of probiotic therapy.

METHODS

We searched the PubMed, EMBASE, INAHTA, HEN and Cochrane Collaboration databases to identify trials in which the prevention or treatment of CDAD with probiotic therapy was the primary or secondary outcome. We extracted data on the number of patients randomly assigned to receive probiotic or placebo, the number of patients with CDAD, the type of probiotic, criteria for diagnosing CDAD, persistence of infection after treatment, compliance and adverse effects.

RESULTS

We identified 4 eligible studies in which prevention (n = 1) or treatment (n = 3) of CDAD was the primary outcome. The benefit of probiotic therapy seen in 2 of the studies was restricted to subgroups characterized by severe CDAD and increased use of vancomycin. The remaining 2 studies were too methodologically flawed for us to draw meaningful conclusions. We also identified 4 trials in which prevention of antibiotic-associated diarrhea with probiotics was the primary outcome and prevention of CDAD a secondary outcome. These studies were limited primarily by too few CDAD cases and provided no evidence of effective prophylaxis. Overall, heterogeneity in choice and dose of probiotic and in criteria for diagnosing CDAD makes it difficult to synthesize information from the 8 studies.

INTERPRETATION

Studies conducted to date provide insufficient evidence for the routine clinical use of probiotics to prevent or treat CDAD. Better designed and larger studies are needed.

Effects of feeding an infant formula containing Lactobacillus GG on the colonization of the intestine: a dose-response study in healthy infants

OBJECTIVES

This study aimed to determine whether feeding Lactobacillus GG (LGG) at varying levels (10 to 10 cfu/day) would result in colonization, defined as > or =1,000 cfu of LGG per gram of stool in 3 of 5 samples collected during the feeding period.

METHODS

Infants received unsupplemented formula during a 7-day baseline, 1 of 4 formulas containing 0 (control), 10 (low), 10 (medium), or 10 (high) cfu of LGG per day during a 2-week test, and unsupplemented formula during a 2-week follow-up. Baseline, test, and follow-up stool samples were evaluated for levels of viable LGG.

RESULTS

During test, supplemented infants were colonized, compared with control (P < 0.05). Median stool counts of LGG (log10 cfu/g) in colonized infants were 5.24 (low), 6.05 (medium), and 5.97 (high). LGG persisted in the stools for 7 to 14 days after discontinuing LGG. No differences were observed among groups in stool consistency, flatulence, fussiness, or adverse events.

CONCLUSION

A 2-week oral administration of 10 to 10 cfu/day LGG was well tolerated; all levels successfully colonized the intestinal tract of healthy, term infants.

Evaluation of Lactobacillus pentosus WE7 for prevention of diarrhea in neonatal foals

OBJECTIVE

To evaluate the efficacy of Lactobacillus pentosus WE7, an equine-origin organism with potentially beneficial in vitro properties, as a probiotic for prevention of neonatal diarrhea in foals.

DESIGN

Randomized controlled clinical trial.

ANIMALS

153 foals.

PROCEDURE

Foals were enrolled at 24 to 48 hours of age and randomly assigned to treatment or control groups. The treatment group received approximately 2 x 10(11) CFU of freeze-dried L. pentosus WE7 orally once daily for 7 days, whereas the control group received a placebo. Clinical monitoring was performed for 14 days.

RESULTS

Probiotic administration was significantly associated with development of signs of depression, anorexia, and colic and the need for veterinary examination and treatment. Probiotic-treated foals also had more days of diarrhea, compared with the control group, although not significantly. In a multivariate model, probiotic administration was significantly associated with development of diarrhea and diarrhea plus additional clinical abnormalities.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of L. pentosus WE7 did not prevent diarrhea; rather, it was associated with development of diarrhea and, most importantly, development of diarrhea plus additional clinical abnormalities and the need for veterinary intervention. The promising in vitro properties of L. pentosus WE7 were not evident in vivo. Results raise concern about the variety of untested probiotic products that are commercially available. Safety and efficacy testing needs to be performed for all potential equine probiotics.

A randomized, double-blind trial of Lactobacillus GG versus placebo in addition to standard maintenance therapy for children with Crohn's disease

Probiotics are widely used by patients with Crohn's disease (CD) in an attempt to improve their health, but few controlled studies have been done to evaluate the efficacy of these therapies. We conducted a randomized, placebo-controlled trial of the probiotic Lactobacillus rhamnosus strain GG (LGG) to see if the addition of LGG to standard therapy prolonged remission in children with CD. Concomitant medications allowed in the study included aminosalicylates, 6-mercaptopurine, azathioprine, and low-dose alternate day corticosteroids. Seventy-five children (age range, 5-21 yr) with CD in remission were randomized to either LGG (n=39) or placebo (n=36) and followed for up to 2 years. The median time to relapse was 9.8 months in the LGG group and 11.0 months in the placebo group (P=0.24); 31% (12/39) of patients in the LGG group developed a relapse compared with 6/36 (17%) of the placebo group (P=0.18). The LGG was well tolerated, with a side effect profile comparable with placebo. This study suggests that LGG does not prolong time to relapse in children with CD when given as an adjunct to standard therapy.

Alive and dead Lactobacillus rhamnosus GG decrease tumor necrosis factor-alpha-induced interleukin-8 production in Caco-2 cells

Certain probiotic bacteria show anti-inflammatory activity after being heat killed, whereas others do not, suggesting that the gastrointestinal environment may alter the activity of probiotic bacteria. Occasionally, probiotics are provided when a patient is also being treated with oral antibiotics; this may have an effect on the probiotic activity. We hypothesized that Lactobacillus rhamnosus GG (LGG) are capable of downregulating tumor necrosis factor-alpha (TNFalpha)-induced interleukin (IL)-8 production under all 3 of these conditions, and that LGG act through the nuclear factor kappaB (NFkappaB)/inhibitor of kappaB (IkappaB) pathway. Caco-2 cells were treated with live or heat-killed LGG in doses ranging from 10(4) to 10(10) cfu/L, in the presence or absence of antibiotics and TNFalpha in the media. TNFalpha-induced production of IL-8 by Caco-2 cells was modulated by LGG under all 3 conditions. However, higher doses of live LGG without TNFalpha in the presence or absence of antibiotics in vitro induced the production of IL-8 (P = 0.001). Heat-killed LGG also blunted the TNFalpha-induced IL-8 production (P < 0.01), but by itself did not increase IL-8 production at higher doses as markedly as live LGG (P < 0.05). LGG reduced the TNFalpha-induced NFkappaB translocation to the nucleus and lessened the decrease in IkappaB in the cytoplasm (P < 0.05). LGG reduced TNFalpha-induced IL-8 production by affecting the NFkappaB/IkappaB pathway in Caco-2 cells. High doses of live LGG markedly increased IL-8 production, but heat-killed LGG caused only a slight increase in IL-8. Thus, heat-killed LGG may effectively ameliorate inflammation with a lower potential than live LGG at high doses to cause inflammation.

Probiotics used in human studies

GOAL

To investigate the literature from 1980 to 2004 for the types of studies and organisms used as probiotics in human studies and diseases.

METHODS

PubMed search for probiotic organisms used in studies from 1980 to August 2004. The data from those papers were evaluated for organisms used, dose, vehicle, frequency, and investigator's report of positive or negative results.

RESULTS

A total of 185 manuscripts were identified. Investigators reported results of both single and multiple organisms in the same manuscript. A single organism was used in 125 reports, and multiple organisms, ranging from 2 to 9, were used in 60 reports. Positive results were reported in 239 clinical situations and negative results reported in 49 in a total of 288 clinical conclusions drawn by the respective investigators. The studies are tabulated in this review.

CONCLUSION

There is a large literature available in credible journals that report benefit of probiotic administration using a wide range of doses, organisms, and clinical situations. Most of the studies are simple reports of a clinical situation and require additional evaluation.

Probiotics: do they have a role in oral medicine and dentistry?

This review describes current knowledge on probiotic bacteriotherapy from the oral health perspective. Recent experimental studies and results from randomized controlled trials have shown that certain gut bacteria, in particular species of Lactobacillus and Bifidobacterium, may exert beneficial effects in the oral cavity by inhibiting cariogenic streptococci and Candida sp. Probiotics have been successfully used to control gastro-intestinal diseases. They also appear to alleviate symptoms of allergy and diseases with immunological pathology. The mechanisms of probiotic action appear to link with colonization resistance and immune modulation. Lactic acid bacteria can produce different antimicrobial components such as organic acids, hydrogen peroxide, carbon peroxide, diacetyl, low molecular weight antimicrobial substances, bacteriocins, and adhesion inhibitors, which also affect oral microflora. However, data is still sparse on the probiotic action in the oral cavity. More information is needed on the colonization of probiotics in the mouth and their possible effect on and within oral biofilms. There is every reason to believe that the putative probiotic mechanisms of action are the same in the mouth as they are in other parts of the gastrointestinal tract. Because of the increasing global problem with antimicrobial drug resistance, the concept of probiotic therapy is interesting and pertinent, and merits further research in the fields of oral medicine and dentistry.

Bacteriotherapy and probiotics’ role on oral health

Oral infections constitute some of the most common and costly forms of infections in humans. The concept of microbial ecological change as a mechanism for preventing dental disease is an important one while altered microbial ecology may lead to dental disease. New methods such as probiotic approaches (i.e. whole bacteria replacement therapy) to eliminate pathogenic members of the microbiota can be investigated. Bacteriotherapy is an alternative and promising way to combat infections by using harmless bacteria to displace pathogenic microorganisms. Probiotics are one of these new agents which are widely used for their therapeutic action. Limited research is available showing that some probiotic cultures may help dental improvement. Present paper focuses on possible oral benefits of probiotics.

A randomized formula controlled trial of Bifidobacterium lactis and Streptococcus thermophilus for prevention of antibiotic-associated diarrhea in infants

GOALS

This clinical trial was carried out to determine whether oral treatment with a commercial probiotic formula containing Bifidobacterium lactis and Streptococcus thermophilus would reduce the frequency of antibiotic-associated diarrhea (AAD) in infants.

STUDY

In this double-bind formula controlled study, 80 infants, 6 to 36 months of age, were randomly assigned to receive a commercial formula containing 10 viable cells of B. lactis and 10 viable cells of S. thermophilus at the initiation of antibiotics for a duration of 15 days. The infants were assessed daily for formula intake, stool frequency, and stool consistency for a total duration of 30 days. Seventy-seven infants received nonsupplemented formula for the entire duration.

RESULTS

There was a significant difference in the incidence of AAD in the children receiving probiotic-supplemented formula (16%) than nonsupplemented formula (31%).

CONCLUSIONS

The present study shows that prevention against AAD in infants was obtained by oral treatment with daily dose of B. lactis and S. thermophilus.

Saccharomyces boulardii in the prevention of antibiotic-associated diarrhoea in children: a randomized double-blind placebo-controlled trial

BACKGROUND

Co-treatment with Saccharomyces boulardii appears to lower the risk of antibiotic-associated diarrhoea in adults receiving broad-spectrum antibiotics.

AIM

To determine whether S. boulardii prevents antibiotic-associated diarrhoea in children.

METHODS

A total of 269 children (aged 6 months to 14 years) with otitis media and/or respiratory tract infections were enrolled in a double-blind, randomized placebo-controlled trial in which they received standard antibiotic treatment plus 250 mg of S. boulardii (experimental group, n = 132) or a placebo (control group, n = 137) orally twice daily for the duration of antibiotic treatment. Analyses were based on allocated treatment and included data from 246 children.

RESULTS

Patients receiving S. boulardii had a lower prevalence of diarrhoea (> or =3 loose or watery stools/day for > or =48 h occurring during or up to 2 weeks after the antibiotic therapy) than those receiving placebo [nine of 119 (8%) vs. 29 of 127 (23%), relative risk: 0.3, 95% confidence interval: 0.2-0.7]. S. boulardii also reduced the risk of antibiotic-associated diarrhoea (diarrhoea caused by Clostridium difficile or otherwise unexplained diarrhoea) compared with placebo [four of 119 (3.4%) vs. 22 of 127 (17.3%), relative risk: 0.2; 95% confidence interval: 0.07-0.5]. No adverse events were observed.

CONCLUSION

This is the first randomized-controlled trial evidence that S. boulardii effectively reduces the risk of antibiotic-associated diarrhoea in children.

Prebiotic effect of fructo-oligosaccharide supplemented term infant formula at two concentrations compared with unsupplemented formula and human milk

BACKGROUND

Human milk components, including oligosaccharides, affect the gastrointestinal flora of infants. Previous studies in adults have demonstrated that fructo-oligosaccharides increase potentially beneficial fecal bacteria, including bifidobacteria. The purpose of this study was to determine the prebiotic effect of infant formula supplemented with fructo-oligosaccharides.

METHODS

Healthy term infants 2 to 6 weeks of age were enrolled in a 5-week, prospective, randomized, crossover, single-site study with a nonrandomized human milk comparator group. Washout weeks preceded and followed a week of feeding with fructo-oligosaccharide-supplemented formula (1.5 or 3.0 g/L). Stool specimens were quantitatively cultured weekly for bacteroides, lactobacilli, bifidobacteria, clostridia and enterococci and were tested for Clostridium difficile toxin.

RESULTS

Seventy-two of 87 infants completed the trial; 58 were formula fed and 14 were human milk fed. Mean counts of bifidobacteria and lactobacilli were similar in all groups at entry and no group experienced a significant change in counts with fructo-oligosaccharide supplementation. After 7 days of fructo-oligosaccharide supplementation the bifidobacteria counts were greater in the 1.5 g/L fructo-oligosaccharide formula group than in the human milk fed or 3.0 g/L fructo-oligosaccharide formula groups. Formula-fed infants had higher counts of enterococci and bacteroides before fructo-oligosaccharide supplementation, and these counts did not change after supplementation. Clostridium counts increased 7 days after supplementation in the 1.5 g/L fructo-oligosaccharide formula group (P = 0.0356). No human milk fed infants had C. difficile toxin in stools. Fructo-oligosaccharide (3.0 g/L) supplementation resulted in more frequent and significantly softer stools.

CONCLUSIONS

Infant formula supplemented with 1.5 or 3.0 g/L fructo-oligosaccharides was safe but had minimal effect on fecal flora and C. difficile toxin.

Probiotics and gastrointestinal diseases

There is increasing evidence indicating health benefits by consumption of foods containing microorganisms, i.e. probiotics. A number of clinical trials have been performed to evaluate the effects in the prevention and treatment of gastrointestinal diseases caused by pathogenic microorganisms or by disturbances in the normal microflora. Gastrointestinal infections caused by Helicobacter pylori, traveller's diarrhoea, rotavirus diarrhoea, antibiotic-associated diarrhoea (AAD) and Clostridium difficile-induced diarrhoea are conditions that have been studied. There are also studies performed on the preventive effect of probiotics on radiation-induced diarrhoea and diarrhoea in tube-fed patients. Inflammatory bowel disease and irritable bowel syndrome, two idiopathic conditions where alterations in the normal microflora have been implicated as responsible for initiation, are two further areas where the use of probiotics has been regarded as promising. The results from clinical studies have not been conclusive in that the effects of probiotics have been strain-dependent and different study designs have been used. Treatment of acute diarrhoea in children and prevention of AAD are the two most justified areas for the application of probiotics.

Current and potential uses of probiotics

OBJECTIVE

To present data that support the current and potential use of probiotics in treating or preventing allergic disorders of the gastrointestinal tract and other disorders.

DATA SOURCES

Case reports, double-blind studies, and animal studies were reviewed.

STUDY SELECTION

Studies were selected based on the expert opinion of the authors.

CONCLUSIONS

Well-designed research studies suggest that supplementary consumption of certain probiotic strains may temporarily alter the intestinal microflora of infants and children to produce a beneficial effect. However, generalization of probiotic effects must not be made and critical scientific evaluation must be used in directing patients to select the appropriate probiotic.

Antagonistic activities of lactobacilli and bifidobacteria against microbial pathogens

The gastrointestinal tract is a complex ecosystem that associates a resident microbiota and cells of various phenotypes lining the epithelial wall expressing complex metabolic activities. The resident microbiota in the digestive tract is a heterogeneous microbial ecosystem containing up to 1 x 10(14) colony-forming units (CFUs) of bacteria. The intestinal microbiota plays an important role in normal gut function and maintaining host health. The host is protected from attack by potentially harmful microbial microorganisms by the physical and chemical barriers created by the gastrointestinal epithelium. The cells lining the gastrointestinal epithelium and the resident microbiota are two partners that properly and/or synergistically function to promote an efficient host system of defence. The gastrointestinal cells that make up the epithelium, provide a physical barrier that protects the host against the unwanted intrusion of microorganisms into the gastrointestinal microbiota, and against the penetration of harmful microorganisms which usurp the cellular molecules and signalling pathways of the host to become pathogenic. One of the basic physiological functions of the resident microbiota is that it functions as a microbial barrier against microbial pathogens. The mechanisms by which the species of the microbiota exert this barrier effect remain largely to be determined. There is increasing evidence that lactobacilli and bifidobacteria, which inhabit the gastrointestinal microbiota, develop antimicrobial activities that participate in the host's gastrointestinal system of defence. The objective of this review is to analyze the in vitro and in vivo experimental and clinical studies in which the antimicrobial activities of selected lactobacilli and bifidobacteria strains have been documented.

Preparing children for travel to tropical and developing regions

Visiting a grandparent for a first time, exploring the ruins of an ancient civilization in a distant country, or river rafting through a tropical jungle are all moments that are never forgotten. Illness, visits to the doctor, and disability should not be a part of these experiences. Diseases such as malaria, yellow fever, travelers' diarrhea, and hepatitis A are preventable. Through the use of vaccines, prophylactic medications, and disease-prevention education, clinicians may help ensure their pediatric patients have enjoyable and rewarding travel experiences.

Yogurt and gut function

In recent years, numerous studies have been published on the health effects of yogurt and the bacterial cultures used in the production of yogurt. In the United States, these lactic acid-producing bacteria (LAB) include Lactobacillus and Streptococcus species. The benefits of yogurt and LAB on gastrointestinal health have been investigated in animal models and, occasionally, in human subjects. Some studies using yogurt, individual LAB species, or both showed promising health benefits for certain gastrointestinal conditions, including lactose intolerance, constipation, diarrheal diseases, colon cancer, inflammatory bowel disease, Helicobacter pylori infection, and allergies. Patients with any of these conditions could possibly benefit from the consumption of yogurt. The benefits of yogurt consumption to gastrointestinal function are most likely due to effects mediated through the gut microflora, bowel transit, and enhancement of gastrointestinal innate and adaptive immune responses. Although substantial evidence currently exists to support a beneficial effect of yogurt consumption on gastrointestinal health, there is inconsistency in reported results, which may be due to differences in the strains of LAB used, in routes of administration, or in investigational procedures or to the lack of objective definition of "gut health." Further well-designed, controlled human studies of adequate duration are needed to confirm or extend these findings.

Benefits of oral supplementation with and without synbiotics in young children with acute bacterial infections

Acutely ill children (n = 129) aged 1-6 years receiving antibiotic therapy were randomized to receive a nutritional supplement with (PS) or without (P) synbiotics or a fruit-flavored drink (D) with their medications. Group PS had significantly greater weight gains (versus D) following antibiotic therapy. The percentages of subjects without bacterial illnesses 14 days following antibiotic therapy were as follows: 94.3% (PS), 87.8% (D), and 80.6% (P). PS (vs D) significantly increased fecal Lactobacillus in a subset of subjects. Oral supplements increase energy intake and promote weight gain in acutely ill children receiving antibiotics; synbiotics may confer additional benefits by increasing bifidobacteria levels.

The effect of Lactobacillus rhamnosus on enterohemorrhagic Escherichia coli infection of human intestinal cells in vitro

There are many examples of probiotic effects of various lactic bacteria on enteropathogens. In this study, Lactobacillus strains (L. rhamnosus, L. gasseri, L. casei and L. plantarum) were tested in an in vitro model of enterohemorrhagic Escherichia coli (EHEC) infection of a human colon epithelial cell line, C2BBe1. While the adhesion and colonization of EHEC was not affected by any of the lactobacillus strains tested, the internalization of EHEC into the cell line was markedly suppressed by L. rhamnosus, though not by others. Concerning the possible mechanisms, the viabilities of EHEC and host cell were not affected by the presence of L. rhamnosus. Simple competitions at certain receptors were unlikely because the suppressive effect on EHEC internalization was strictly dependent on viable L. rhamnosus and could not be observed with the conditioned medium or killed L. rhamnosus. The fact that L. rhamnosus showed outstanding potential for adhering to the colon epithelial cell line, compared with other strains, suggested that an avid interaction between L. rhamnosus and the host cell might be modulating intra-cellular events responsible for the internalization of EHEC.

Probiotic use in children

Interest in nutritional supplements and functional foods has risen significantly in recent years. Many of the products that are marketed to consumers tout the benefits of probiotics for general good health and for a wide variety of conditions and situations. Although most of these products have been used safely for years, careful analysis of scientific research should be conducted before routinely recommending these products, especially for children. A basic understanding of intestinal flora, properties of probiotics, and clinical research findings is necessary for clinicians to delineate the role of probiotic agents in the pediatric population.

Enteral feeding of premature infants with Saccharomyces boulardii

BACKGROUND

Saccharomyces boulardii (SB) is a yeast that acts both as a probiotic and as a polyamine producer. Probiotics prevent the overgrowth of pathogens in the gut while polyamines enhance intestinal maturation. The aim of this randomized study was to investigate the ability of SB to modify the gut microbial ecology and its function.

METHODS

A total of 87 healthy babies with gestational age 28-32 weeks were studied. They were randomly assigned to receive a preterm formula to which SB or maltodextrins was added for 30 days. Evaluations were made on the following: SB tolerance and weight gain, faecal flora analysis, intestinal D-xylose absorption and faecal lipid excretion.

RESULTS

SB was well tolerated by the infants. There was no difference in weight gain between the two groups. Median log of colony forming units per gram of faeces for Escherichia coli and enterococci was significantly lower in the SB group [E. coli: 2.67 (0.045) vs. 2.75 (0.058), P<0.001; enterococci: 2.14 (0.359) vs. 2.19 (0.138), P<0.05]. On the other hand, the number of bifidobacteria and staphylococci in the stools was significantly higher in the SB group [bifidobacteria: 2.65 (0.083) vs. 2.27 (0.075), P<0.001; staphylococci: 1.23 (0.869) vs. 0.6 (0.281), P<0.001]. D-Xylose and lipid absorption was not improved by SB [median blood D-xylose: 1.5 (0.4) mmol/l vs. 1.35 (0.3) mmol/l, P>0.1; median stool steatocrit: 64% (3.05%) vs. 65% (2.72%) P>0.5].

CONCLUSIONS

An SB-supplemented formula is well tolerated by preterm infants, it has a beneficial effect on stool flora bringing it closer to that of breast fed babies but it does not improve D-xylose or lipid gut absorption.

Probiotics, antibiotic-associated diarrhoea and Clostridium difficile diarrhoea in humans

Probiotics are living organisms which, when ingested, have a beneficial therapeutic effect. Examples are bacteria, especially Lactobacillus rhamnosus GG, and the yeast Saccharomyces boulardii. Controlled trials indicate a benefit of both of these in the prevention of antibiotic-associated diarrhoea. Other less effective probiotics are Lactinex, Enterococcus faecium and bifidobacteria. In the difficult clinical problem of recurrent Clostridium difficile disease, S. boulardii as an adjunct to antibiotics has shown benefit in controlled trials. There is, however, less convincing evidence for the efficacy of Lactobacillus GG in this disease. Additional controlled trials and safety studies are needed before there can be a widespread endorsement of probiotics for these two conditions.

A randomized trial of yogurt for prevention of antibiotic-associated diarrhea

Antibiotic-associated diarrhea (AAD) is the most common adverse effect of antibiotic therapy. Our aim was to determine the effectiveness of a dietary supplement of yogurt for prevention of AAD. Two hundred two hospitalized patients receiving oral or intravenous antibiotics were randomized to receive or not receive a dietary yogurt supplement, consisting of 227 grams of commercial yogurt, and followed for 8 days. Mean age of the study group was 70 years and 43% were male. Compliance and 8-day follow-up were 85% and 91%, respectively. Patients receiving yogurt reported less frequent diarrhea (12% vs 24%; P = 0.04), and significantly less total diarrhea] days (23 vs 60). The cumulative proportions of patients without diarrhea were significantly different (P = 0.02) between patients receiving and not receiving yogurt. For conclusion, dietary supplementation with yogurt is a simple, effective, and safe treatment that decreases the incidence and duration of AAD.

Probiotics to enhance anti-infective defences in the gastrointestinal tract

Several clinical studies have demonstrated the therapeutic and/or prophylactic efficacy of specific probiotics against acute viral gastroenteritis and antibiotic-associated diarrhoea (including Clostridium difficile infection). Emerging evidence also suggests beneficial effects against Helicobacter pylori infection. The evidence of efficacy against traveller's diarrhoea remains, however, inconclusive. The precise mechanisms by which probiotics potentiate host gastrointestinal defences and mediate protection are not fully known. There is evidence to suggest, however, that probiotics might contribute to host defence by reinforcing non-immunological defences and stimulating both specific and non-specific host immune responses. Little is known about the relative importance of the probiotic-stimulated mechanisms in host protection. This review summarises the evidence for the anti-infective effects of probiotics and discusses the effect of orally delivered probiotics on non-immunological and immunological defence mechanisms in the host, especially in the gastrointestinal tract.

Acute gastroenteritis in children : what role for antibacterials?

The aim of this article is to define the currently accepted role of antibacterials in the treatment of acute gastroenteritis in children. Most cases of acute gastroenteritis in children are viral, self-limited, and need only supportive treatment. Appropriate fluid and electrolyte therapy, with close attention to nutrition, remain central to therapy.Antibacterial therapy serves as an adjunct, to shorten the clinical course, eradicate causative organisms, reduce transmission, and prevent invasive complications. Selection of antibacterials to use in acute bacterial gastroenteritis is based on clinical diagnosis of the likely pathogen prior to definitive laboratory results. Antibacterial therapy should be restricted to specific bacterial pathogens and disease presentations. In general, infections with Shigella spp. and Vibrio cholera should usually be treated with antibacterials, while antibacterials are only used in severe unresponsive infections with Salmonella, Yersinia, Aeromonas, Campylobacter, Plesiomonas spp., and Clostridium difficile. Antibacterials should be avoided in enterohemorrhagic Escherichia coli infection. However, empiric therapy may be appropriate in the presence of a severe illness with bloody diarrhea and stool leucocytes, particularly in infancy and the immunocompromised. The benefits and risks of adverse drug reactions should be weighed before prescribing antibacterials. Moreover, a major concern is the emergence of antibacterial-resistant strains due to the widespread use of antibacterial agents.

Using probiotics and prebiotics to improve gut health

Recent molecular-based investigations have confirmed the species diversity and metabolic complexity of the human gut microbiota. It is also increasingly clear that the human gut microbiota plays a crucial role in host health, both as a source of infection and environmental insult and, conversely, in protection against disease and maintenance of gut function. Although little is known about the health impact of the dominant groups of gut bacteria it is generally accepted that bifidobacteria and lactobacilli are important components of what might be termed the beneficial gut microbiota. The microbiota management tools of probiotics, prebiotics and synbiotics have been developed and, indeed, commercialized over the past few decades with the expressed purpose of increasing numbers of bifidobacteria and/or lactobacilli within the gastrointestinal tract.

Incidence and risk factors of oral antibiotic-associated diarrhea in an outpatient pediatric population

BACKGROUND

Little information is available on the epidemiologic characteristics of antibiotic-associated diarrhea (AAD) in children. The authors' aim was to evaluate the incidence of AAD in an outpatient pediatric population and to identify risk factors.

METHODS

Children aged 1 month to 15.4 years treated with oral antibiotics for a proven or suspected infection were enrolled from an ambulatory pediatric practice during an 11-month period. Parents recorded the daily frequency and characteristics of stools using a diary during the antibiotic treatment and for 1 week after it was stopped. An episode of diarrhea was defined by at least 3 soft or liquid stools/d for at least 2 consecutive days. Risk factors for AAD-age, type of antibiotic treatment, type of combined treatment, and site of infection-were analyzed.

RESULTS

Of 650 children included, 11% had an episode of AAD, lasting a mean of 4.0 +/- 3.0 days, beginning a mean of 5.3 +/- 3.5 days after the start of antibiotic treatment. No child was hospitalized because of AAD. The incidence of AAD was higher in children less than 2 years (18%) than in those more than 2 years (3%; P < 0.0001). The incidence of AAD was particularly high after administration of certain antibiotics (amoxicillin/clavulanate, 23%; P = 0.003 compared with other antibiotics). The type of combined treatment and site of infection did not influence the onset of AAD.

CONCLUSIONS

Antibiotic-associated diarrhea was common in these outpatient children, especially for those aged less than 2 years and after the prescription of certain antibiotics, particularly, the combination of amoxicillin/clavulanate.

Role of probiotics in the management of patients with food allergy

OBJECTIVE

This review will concentrate on the potential use of probiotics in treating or preventing allergic disorders of the gastro-intestinal tract. In small infants, most reactions to foods are manifested in the gastro-intestinal tract. As children get older, cutaneous and even systemic or respiratory manifestations of food intolerances may be more common. In most instances, allergic disorders in the gut cause inflammation in the mucosa.

DATA SOURCES

Recently, the role of gut microflora in allergic disease has gained increasing interest with reports of probiotics being used to treat food allergy.

STUDY SELECTION

Pertinent scientific reports on the role of probiotics in the management of patients with food allergy will be reviewed. A recent study to determine the effect of very early probiotic colonization will be extensively reviewed as it presents an intriguing concept of a preventive strategy related to food allergy development

RESULTS

Significant improvement has been noted in infants receiving Lactobacillus GG in their extensively hydrolyzed formula.

CONCLUSIONS

It is likely more studies will be forthcoming with different probiotic organisms in the prevention and treatment of allergic disorders in children and adults.

Gut flora in health and disease

The human gut is the natural habitat for a large and dynamic bacterial community, but a substantial part of these bacterial populations are still to be described. However, the relevance and effect of resident bacteria on a host's physiology and pathology has been well documented. Major functions of the gut microflora include metabolic activities that result in salvage of energy and absorbable nutrients, important trophic effects on intestinal epithelia and on immune structure and function, and protection of the colonised host against invasion by alien microbes. Gut flora might also be an essential factor in certain pathological disorders, including multisystem organ failure, colon cancer, and inflammatory bowel diseases. Nevertheless, bacteria are also useful in promotion of human health. Probiotics and prebiotics are known to have a role in prevention or treatment of some diseases.